Method and apparatus for selective operation of a hybrid electric vehicle in various driving modes

ABSTRACT

A hybrid electric vehicle and method that stores an upper energy storage limit and a lower energy storage limit for an energy storage system for each of a plurality of predetermined driving modes, determines a currently selected driving mode from the plurality of predetermined driving modes, sets the upper energy storage limit and the lower energy storage limit for the energy storage system based on the currently selected driving mode, determines parameters for operation of vehicle components within the currently selected driving mode and generates command signals to the vehicle components for operation within determined parameters.

[0001] This is a Continuation-in-Part of Application No. 10/413,544filed Apr. 15, 2003, which in turn is a Continuation-in-Part ofApplication No. 09/748,182 filed Dec. 27, 2000, now U.S. Pat. No.6,573,675 B2 issued Jun. 3, 2003. The entire disclosure of the priorapplications are hereby incorporated by reference herein in itsentirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of Invention

[0003] This invention relates to methods and apparatuses for selectivelyoperating a hybrid electric vehicle in one of a number of driving modes.

[0004] 2. Description of Related Art

[0005] The desire for cleaner air has caused various federal, state, andlocal governments to adopt or change regulations requiring lower vehicleemissions. Increasing urban traffic congestion has prompted a need forincreases in public mass transit services. All mass transit systemsutilizes buses, at least in part, to transport people into, out of, andwithin traffic congested urban areas. Conventional buses use dieselpowered internal combustion engines. Diesel engines produce emissions,including carbon monoxide, that contribute to air pollution. It ispossible to refine cleaner diesel fuel. However, cleaner diesel fuel ismore costly to refine and causes a corresponding increase in the cost ofbus service.

[0006] Alternative fuels have been used to reduce emissions and conserveoil resources. Compressed natural gas has been used as an alternativefuel. Compressed natural gas does not produce as much power inconventional internal combustion engines as gasoline and diesel and hasnot been widely developed or accepted as an alternative to gasoline anddiesel.

[0007] Additives have also been developed for mixing with gasoline toreduce emissions. Ethanol and MTBE have been added to gasoline tooxygenate the combustion of gasoline and reduce emissions of carbonmonoxide. These additives, however, are believed to cause decreased gasmileage and, in the case of MTBE, to be a potential public healththreat.

[0008] Electric vehicles have been developed that produce zeroemissions. Electric vehicles are propelled by an electric motor that ispowered by a battery array on board the vehicle. The range of electricvehicles is limited as the size of the battery array which can beinstalled on the vehicle is limited. Recharging of the batteries canonly be done by connecting the battery array to a power source. Electricvehicles are not truly zero emitters when the electricity to charge thebattery array is produced by a power plant that bums, for example, coal.

[0009] Hybrid electric vehicles have also been developed to reduceemissions. Hybrid electric vehicles include an internal combustionengine and at least one electric motor powered by a battery array. In aparallel type hybrid electric vehicle, both the internal combustionengine and the electric motor are coupled to the drive train viamechanical means. The electric motor may be used to propel the vehicleat low speeds and to assist the internal combustion engine at higherspeeds. The electric motor may also be driven, in part, by the internalcombustion engine and be operated as a generator to recharge the batteryarray.

[0010] In a series type hybrid electric vehicle, the internal combustionengine is used only to run a generator that charges the battery array.There is no mechanical connection of the internal combustion engine tothe vehicle drive train. The electric traction drive motor is powered bythe battery array and is mechanically connected to the vehicle drivetrain.

[0011] Conventional internal combustion engine vehicles controlpropulsion by increasing and decreasing the flow of fuel to thecylinders of the engine in response to the position of an acceleratorpedal. Electric and hybrid electric vehicles also control propulsion byincreasing or decreasing the rotation of the electric motor or motors inresponse to the position of an accelerator pedal. Electric and seriestype hybrid electric vehicles may be unable to accelerate properly ifthe power available from the battery or batteries and/or genset isinsufficient.

[0012] Conventional internal combustion engine vehicles may also includesystems to monitor the slip of a wheel or wheels to thereby control theengine and/or the brakes of the vehicle to reduce the slip of the wheelor wheels. In hybrid electric vehicles, however, it is necessary tocontrol the speed and torque of the electric motor or motors to controlthe slip of wheels.

[0013] Conventional internal combustion engine vehicles may also includesystems to modify effects of vehicle braking in certain situations,including loss of traction, wheel slippage, and load shifting. Inelectric and hybrid electric vehicles, however, regenerative brakingoperation must interface with these and other propulsion systemconditions to prevent unexpected or unsafe operation. Additionally, thissystem must interface with the energy storage and generation systemsbecause it is electrically based. Furthermore, in electric and hybridelectric vehicles, an operator input may be used to manually indicatethe level and types of regenerative braking to be applied.

SUMMARY OF THE INVENTION

[0014] The invention provides methods and apparatus for selectivelyoperating a hybrid electric vehicle in one of a number of driving modes.

[0015] An exemplary embodiment of a method for adaptively controlling ahybrid electric vehicle including an energy generation system, a energystorage system receiving electric current at least from the generationsystem, and at least one electric motor receiving current from theenergy storage system, includes the steps of storing an upper energystorage limit and a lower energy storage limit for the energy storagesystem for each of a plurality of predetermined driving modes,determining a currently selected driving mode from the plurality ofpredetermined driving modes, setting the upper energy storage limit andthe lower energy storage limit for the energy storage system based onthe currently selected driving mode, determining parameters foroperation of vehicle components within the currently selected drivingmode and generating command signals to the vehicle components foroperation within determined parameters.

[0016] According to an exemplary embodiment, a hybrid electric vehicleincludes an energy generation system, a energy storage system receivingelectric current at least from the generation system, and at least oneelectric motor receiving current from the energy storage system, and avehicle controller containing multiple predetermined driving modes. Thecontroller stores an upper energy storage limit and a lower energystorage limit for the energy storage system for each of a plurality ofpredetermined driving modes. determines a currently selected drivingmode from the plurality of predetermined driving modes, sets the upperenergy storage limit and the lower energy storage limit for the energystorage system based on the currently selected driving mode, determinesparameters for operation of vehicle components within the currentlyselected driving mode and generates command signals to the vehiclecomponents for operation within determined parameters.

[0017] Other features of the invention will become apparent as thefollowing description proceeds and upon reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Various exemplary embodiments of this invention will be describedin detail with reference to the following figures, wherein like numeralsreference like elements, and wherein:

[0019]FIG. 1 is schematic view of an exemplary embodiment of a seriestype hybrid electric vehicle according to the invention;

[0020]FIG. 2 is a schematic diagram illustrating an exemplary embodimentof a circuit for controlling charging of the battery array by thegenerator;

[0021]FIG. 3 is a diagram illustrating an exemplary embodiment of acircuit for controlling the electric motors;

[0022]FIG. 4 is a diagram illustrating an exemplary embodiment of acircuit of the motor controllers;

[0023]FIG. 5 is a diagram illustrating the relationship between thepower created, the power stored, and the power consumed by the serieshybrid electric vehicle according to the invention;

[0024]FIG. 6 is a diagram illustrating an exemplary embodiment of amaster control switch;

[0025]FIG. 7 is a diagram illustrating an exemplary embodiment of adriver's input control panel for determining a driving mode;

[0026]FIG. 8 is a diagram illustrating an exemplary embodiment of adriver's input control panel for determining a regenerative brakingmode;

[0027]FIG. 9 is a diagram schematically illustrating an exemplaryembodiment of the relationship between an accelerator pedal and theelectric motors; and

[0028]FIGS. 10-18 are flowcharts illustrating an exemplary adaptivecontrol of the propulsion of the series type hybrid electric vehicle.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0029] Referring to FIG. 1, an exemplary embodiment of a hybrid electricvehicle 10 which embodies the invention includes a plurality of wheels11, 12, 13, and 14 and a vehicle chassis 15. The wheels 13 and 14 arecoupled to electric motors 50 and 60, respectively, through gear boxes52 and 62, respectively. The wheels 13 and 14 are independently mountedto respective suspension components, such as swing arms. In thisembodiment, the wheels 13 and 14 are not coupled together by an axle. Inother embodiments, the wheels 13 and 14 may be coupled together, forexample, by an axle.

[0030] The wheels 13 and 14 may be either the front wheels or the rearwheels of the vehicle 10. In this embodiment, the wheels 11 and 12 arenot driven and may be coupled together by an axle. In other embodiments,the wheels 11 and 12 may be driven.

[0031] Four wheel speed sensors 11′-14′ are provided for sensing therotational speed of each wheel 11-14, respectively.

[0032] In an exemplary embodiment of a vehicle which embodies thisinvention, the vehicle 10 is a bus having an occupancy capacity inexcess of 100. However, it should be appreciated that the vehicle may bea bus of a smaller capacity or that the vehicle may be a smallerpassenger vehicle, such as a sedan. Further, the invention is notlimited to passenger vehicles, the invention can be used in any type ofmotor vehicle, including trucks, boats, etc. In various exemplaryembodiments, the vehicle may be any size and form currently used orlater developed.

[0033] The electric motors 50 and 60 are powered by an energy storagesystem, such as a battery array 30, and are controlled by motorcontrollers 51 and 61, respectively. An energy storage systemtemperature sensor 30′ detects the temperature of the battery array 30.While exemplary embodiments use a battery array, the invention is notlimited to this. Other known or subsequently developed energy storagesystems can be adapted for use with this invention, such as capacitors,ultra capacitors, flywheels or other inertia storing systems, orhydraulic accumulators.

[0034] According to an exemplary embodiment of the vehicle 10, theelectric motors 50 and 60 are synchronous, permanent magnet DC brushlessmotors. Each electric motor 50 and 60 is rated for 220 Hp and 0-11,000rpm. The maximum combined power output of the electric motors 50 and 60is thus 440 Hp. The permanent magnet DC brushless motors includepermanent magnets, such as rare earth magnets, for providing a magneticfield as opposed to AC induction motors which create or induce amagnetic field on the rotating portion of the motor. The DC brushlessmotors are thus inherently more efficient than AC induction motors as nolosses occur from inducing the magnetic field. The DC brushless motorsalso have a more useful torque profile, a smaller form factor, and lowerweight than AC induction motors. The DC brushless motors also requireless energy input for an equivalent power output than AC inductionmotors. However, this invention is not limited to permanent magnet DCbrushless motors, and other types of electric motors, such as ACinduction motors, can be used.

[0035] The hybrid electric vehicle 10 is preferably a series type hybridelectric vehicle that includes an energy generation system, such as agenerator set (genset) 300, 310 including an internal combustion engine300 and a generator 310 that is driven by the internal combustion engine300. The internal combustion engine 300 may be powered by gasoline,diesel, or compressed natural gas. It should be appreciated, however,that the internal combustion engine 300 may be replaced by a fuel cell,turbine or any other number of alternatives for creating usable electricpower.

[0036] According to an exemplary embodiment of the invention, theinternal combustion engine 300 may be a 2.5 liter Ford LRG-425 enginepowered by compressed natural gas. The 2.5 liter Ford LRG-425 engineproduces 70 Hp. It should be appreciated that the power output of suchan engine may be increased by increasing the RPM of the engine anddecreased by decreasing the RPM of the engine. In this embodiment withtwo 220 Hp electric motors 50 and 60 and an internal combustion engine300 operating at 70 Hp, the performance enhancement factor of thevehicle 10 is 440/70, or at least 6.2. Other internal combustion enginescan of course be utilized.

[0037] In this embodiment, the generator 310 is a DC brushless generatorthat produces, for example, 240-400 V_(AC). Other types of generatorsmay be employed. In an exemplary embodiment of the vehicle 10, thegenerator is operated to produce 345 V_(AC) during certain drive modes.

[0038] An output shaft of the internal combustion engine 300 isconnected to the generator 310 to power the generator 310 and the ACvoltage output by the generator 310 is converted to a DC voltage by agenerator controller 320. The converted DC voltage charges the batteryarray 30. The battery array 30 may include, for example, 26 deep cycle,lead-acid batteries of 12 volts each connected in series. It should beappreciated, however, that other batteries, such as nickel cadmium,metal hydride or lithium ion, may be used and that any number ofbatteries can be employed, as space permits. In this embodiment,depending upon the load on the vehicle 10, the battery array voltageranges between 240 and 400 V_(DC).

[0039] An electronic control unit (ECU) 200 includes a programmablelogic controller (PLC) 210 and a master control panel (MCP) 220. The MCP220 receives information from various sensors, such as the wheel speedsensors 11′-14′ and the battery array temperature sensor 30′, andprovides this information to gauges or other outputs in the vehicle 10,as desired. The PLC 210 executes various programs to control variouscomponents of the vehicle 10, for example, the internal combustionengine 300, the generator 310, the generator controller 320, theelectric motors 50 and 60, and the motor controllers 51 and 61.

[0040] Although not shown in the drawings, the vehicle 10 may include acooling system or cooling systems for the internal combustion engine300, the generator controller 320, the battery array 30, the motorcontrollers 51 and 61, and the motors 50 and 60. The cooling system maybe a single system which includes a coolant reservoir, a pump forpumping the coolant through a heat exchanger such as a radiator and afan for moving air across the heat exchanger or a plurality of coolingsystems similarly constructed. The ECU 200 controls the cooling systems,including the pumps and the fans, to perform a heat shedding operationin which the heat generated by the engine 300, the controllers 320, 51,and 61, the battery array 30, the motors 50 and 60, and various othersystems is released to the atmosphere. Any acceptable means and methodsfor cooling the vehicle components may be utilized.

[0041] As shown in FIG. 2, the coils of the generator 310 are connectedto the generator controller 320 by leads 311, 312, and 313. Thegenerator controller 320 includes two switching insulated or isolatedgate bipolar transistors (IGBT) 330 per phase of the generator 310 andtheir corresponding diodes. In an exemplary embodiment including a threephase generator 310, the generator controller 320 includes 6 IGBT 330and six corresponding diodes.

[0042] The PLC 210 controls each IGBT 330 of the generator controller320 to control the conversion of the AC voltage of the generator 310 tothe DC voltage for charging the battery array 30. The PLC 210 may switchone or more of the IGBT 330's off when the SOC of the battery array 30reaches an upper control limit, to stop the conversion of the AC voltageto DC voltage and prevent overcharging of the battery array 30.

[0043] According to an exemplary embodiment of the invention, the engine300 runs continuously during operation of the vehicle 10 andcontinuously turns the shaft 315 of the generator 310. The PLC 210switches each IGBT 330 on and off via high speed pulse width modulation(PWM) to control charging of the battery array 30. It should beappreciated however that the PLC 210 may control the charging of thebattery array 30 by turning the engine 300 on and off, or in thealternative, by changing the RPM's of the engine 300.

[0044] A possible control circuit for the electric motors 50 and 60 isillustrated in FIG. 3, and includes the motor controllers 51 and 61. Themotor controllers 51 and 61 receive power from the battery array 30 anddistribute the power to the electric motors 50 and 60 by switches B1-B6of pulse width modulation (PWM) inverters 54 and 64. The PWM inverters54 and 64 generate AC current from the DC current received from thebattery array 30. The battery current I_(B) is distributed by theswitches B1-B6, for example IGBT, of the PWM inverters 54 and 64 intomotor currents I₁, I₂, and I₃ for driving the motors 50 and 60.

[0045] The motor controllers 51 and 61 distribute the battery currentI_(B) via the switches B1-B6 by factoring feedback from position sensors53 and 63 and encoders 56 and 66 that determine the timing or pulsing ofelectromagnets of the motors 50 and 60. The pole position sensors 53 and63 determine the pole positions of the permanent magnets of the motors50 and 60 and the encoders 56 and 66 determine the phase angle. Itshould be appreciated that each pair of pole position sensors 53 and 63and encoders 56 and 66, respectively, may be replaced by a phaseposition sensor and the phase change frequency may be read to determinethe speed of rotation of the electric motors 50 and 60.

[0046] The motor controllers 51 and 61 calculate the motor connectorvoltages U₁₂, U₃₁, and U₂₃ based on the rotary velocity and the knownflux value of the motors 50 and 60 between the motor connectors. Theoperating voltage of the inverters 54 and 64 is then determined by therectified voltages of the diodes of the switches B1-B6 or by the voltageUi of an intermediate circuit including a capacitor C. If the voltage Uibecomes larger than the battery voltage U_(B), uncontrolled current mayflow to the battery array 30. Voltage sensors 55 and 65 determine thevoltage Ui and the motor controllers 51 and 61 compare the voltage Ui tothe battery voltage U_(B). The motor controllers 51 and 61 activate theswitches B1-B6 to cause magnetizing current to flow directly to themotors 50 and 60 to avoid unnecessary recharging of the battery array30.

[0047] As shown in FIG. 3, each motor controller 51 and 61 receivescontrol data from the ECU 200 through a controller area network (CAN).The ECU 200 can communicate with the various sensors and the motorcontrollers 51 and 61 by, for example, DeviceNet™, an open, globalindustry standard communication network.

[0048] Referring to FIG. 4, each motor controller 51 and 61 includes acontrol unit 101 including a field axis current and torque axis currentdetector 102. The detector 102 calculates the torque axis current I_(t)and the field axis current I_(f) of each motor 50 and 60 by executing a3-phase, 2-phase coordinate transfer from the input of the currentdetectors 57 and 67 that measure the 3-phase AC current of the motors 50and 60 and the phase calculator 108 that received input from the poleposition sensors 53 and 63 and the encoders 56 and 66. The torque axiscurrent I_(t) and the field axis current I_(f) calculated by thedetector 102 are input to a field axis current and torque axis currentcontrol unit 103. The current control unit 103 receives a field axiscurrent reference value I_(fref) from a field axis current referencecontrol unit 104 and receives a torque axis current reference valueI_(tref) from a torque axis current reference control unit 105.

[0049] The reference control units 104 and 105 determine the currentreference values I_(fref) and I_(tref) by comparing a torque referencevalue T_(ref) (which is determined by the position of an acceleratorpedal of the vehicle) with the actual rotational velocity determined byan rpm calculator 106 that receives input from the encoders 56 and 66. A⅔ phase changer 107 receives input from a phase calculator 108 andcalculates the 3-phase AC reference values by performing a2-phase/3-phase coordinate transformation. A PWM control unit 109generates a PWM signal by comparing the 3-phase reference values with atriangular wave signal which is input to the PWM inverters 54 and 64.

[0050] Referring to FIG. 5, the relationship between the powergenerated, the power stored, and the power consumed over time, by theseries hybrid electric vehicle 10 according to the invention will beexplained.

[0051] Power is consumed from the battery array 30 by the electricmotors 50 and 60 during acceleration of the vehicle 10 to a cruisingspeed. As shown in FIG. 5, the vehicle 10 reaches cruising speed at timet₁, which corresponds to a peak power P_(peak) of the electric motors 50and 60. The peak power P_(peak) of the electric motors 50 and 60 isdependent on the driving mode (discussed below) of the vehicle 10selected by the operator. In the exemplary embodiment of the inventionin which the electric motors 50 and 60 are each 220 Hp, the peak powerP_(peak) consumed by the electric motors 50 and 60 is 440 Hp.

[0052] The power consumption (traction effort) of the electric motors 50and 60 during acceleration is represented by the curve below thehorizontal axis and the area defined by the curve below the horizontalaxis between the times t₀ and t₂ represents the total power consumptionof the vehicle 10 during acceleration. In the event that the SOC of thebattery array 30 is insufficient to achieve the cruising speed, the ECU200 controls the motor controllers 51 and 61 to limit the peak powerP_(peak) the electric motors 50 and 60 may draw from the battery array30. After the vehicle 10 has accelerated to cruising speed, the tractioneffort of the electric motors 50 and 60 may be reduced between the timet₁, and the time t₂, and the power consumption by the electric motors 50and 60 may also be reduced.

[0053] The cruising speed of the vehicle 10 is maintained between thetime t₂ and the time t₃. In this embodiment, during the time between t₂and t₃, the genset 300, 310 is operated to produce power P_(gen) higherthan the power consumption (traction effort) of the electric motors 50and 60 necessary to maintain the vehicle's cruising speed. Thedifferential in power between the traction effort and the powergenerated P_(gen) is stored in the battery array 30.

[0054] The power P_(gen) generated by the genset 300,310, in thisembodiment, is dependent on the rpm of the engine 300 and a user demandsignal sent to the genset 300, 310 that is controlled by the ECU 200.The ECU 200 controls the engine 300 to generally maintain the rpm of theengine 300, and the power generated P_(gen), constant. However, itshould be appreciated that the ECU 200 may control the engine 300 toreduce or increase the rpm of the engine 300, and thus the reduce orincrease, respectively, the power generated P_(gen).

[0055] The power generated P_(gen) by the genset 300,310 may be reducedif the SOC of the battery array 30 approaches an upper control limit atwhich the battery array 30 may become overcharged. The power generatedP_(gen) by the genset 300, 310 may be increased if the SOC of thebattery array 30 approaches a lower control limit at which the batteryarray 30 would be unable to drive the electric motors 50 and 60 withenough torque to propel the vehicle 10. In an exemplary embodiment ofthe vehicle 10 in which the engine 300 is a 2.5 liter Ford LRG-425engine powered by compressed natural gas, the power generated P_(gen) is70 Hp.

[0056] Regenerative braking occurs between the times t₃ and t₄ when thevehicle 10 decelerates after release of the accelerator pedal or whenthe vehicle 10 travels on a downhill slope at a constant speed. Duringregenerative braking, the electric motors 50 and 60 function asgenerators and current is supplied to the battery array 30 by theelectric motors 50 and 60. The power generated P_(braking) duringregenerative braking is stored in the battery array 30.

[0057] The power generated by the genset 300,310 during maintenance ofthe cruising speed and the power generated by regenerative brakingP_(braking) is represented by the curve above the horizontal axis andthe area A₂ defined by the curve above the horizontal axis representsthe total energy creation and storage of the vehicle 10 duringmaintenance of the cruising speed and regenerative braking.

[0058] The power P_(gen) of the genset 300, 310 and the regenerativebraking power P_(braking) are controlled by the ECU 200 to substantiallyequal the energy consumption (traction effort) of the electric motors 50and 60 during acceleration. In other words, the area A₁ defined by thecurve below the horizontal axis is equal to the area A₂ defined by thecurve above the horizontal axis. The ECU 200 controls the tractioneffort of the electric motors 50 and 60 (including the peak powerP_(peak)) and the power generated P_(gen) so that the power generatedand the power stored do not exceed the power consumed, and vice versa,so as to maintain the SOC of the battery array 30 within a range ofcontrol limits. The ECU 200 controls the power generated P_(gen), andthe traction effort of the electric motors 50 and 60 so that the amperehours during energy consumption do not exceed the thermal capacity ofthe battery array during power creation and storage.

[0059] An exemplary method for adaptively controlling the state ofcharge SOC of the battery array 30 is disclosed in U.S. patentapplication Ser. No. 09/663,118, filed Sep. 15, 2000, now U.S. Pat. No.6,333,620, the entire contents of which are herein incorporated byreference.

[0060] The ECU 200 also stores a plurality of settings and limits forsystems and devices according to various vehicle driving modes(discussed below). For example, the ECU 200 stores a plurality of presetstate of charge upper control limits UCL and state of charge lowercontrol limits LCL for the battery array 30 based on the current vehicledriving mode. The ECU 200 can also store a plurality of preset valuesfor an upper torque limit, a power generation limit, a speed limit or anupper generation limit for the genset 300, 310. These predeterminedsettings and limits may be established from look-up tables in the ECU200, by adaptive determination of the ECU 200 as a result of variousother inputs and states, or may be set manually by an operator or atechnician. As should be appreciated, additional methods for determiningthese settings and limits may be used as they are developed or becomeavailable.

[0061] The driving mode in which the vehicle 10 should be operating willbe described based on the position of a switch. However, the drivingmode may be automatically determined by sensors on the vehicle 10, e.g.,a GPS, radio, mechanical trip, mileage counter, etc. mounted on thevehicle 10 which may interact with transmitters along the routetraversed by the vehicle 10. As such, when the vehicle 10 is operationin an unsafe vehicle condition, for example when the SOC of the batteryarray 30 is low, the ECU 200 determines a driving mode that willeliminate the unsafe condition and thereafter operate the vehicle 10 inthat driving mode. The vehicle 10 can also be operated from a remotelocation via a radio or other signaling method. It should also beappreciated that any automatic means currently available or laterdeveloped can be used for the vehicle 10 to determine the location ofthe vehicle 10, and thus determine what driving mode the vehicle 10should be in. Also, a visible (e.g., a sign) or an audible signalmechanism could signal to the driver as to the driving mode the vehicle10 should be operating in, and the driver could supply this informationto the MCP 220.

[0062] This embodiment includes a master control switch. Referring toFIG. 6, a master control switch 20 positioned, for example, in anoperator area of the vehicle 10, includes an OFF position, a DRIVEENABLE position and an ENGINE RUN position. Any acceptable switchmechanism can be employed. The rotary switch 20 in FIG. 6 is merely anexample of an acceptable switch. The position of the switch 20 is inputto the MCP 220. When the switch 20 is moved to the DRIVE ENABLEposition, the PLC 210 controls the electric motors 50 and 60 to run thevehicle in a driver selected zero emissions mode by drawing power fromthe battery array 30. The engine 300 is not operated during the zeroemissions mode, i.e., when the switch 20 is in the DRIVE ENABLEposition. The range of the vehicle 10 in zero emissions mode is limitedas the SOC of the battery array 30 will eventually be lowered below alevel sufficient to drive the electric motors 50 and 60 to propel thevehicle.

[0063] When the switch 20 is moved to the ENGINE RUN position, the ECU200 instructs the generator 310 to operate as a motor for starting theengine 300. During the starting of the engine 300, the generator 310receives current from the battery array 30. The current is supplieduntil the engine 300 reaches a predetermined idling speed and then thecurrent supply is stopped. The engine 300 then drives the generator 310to charge the battery array 30, as necessary.

[0064] The ECU 200 controls the engine 300 by monitoring the enginespeed (rpm) as sensed by a tachometer (not shown) and the fuel mixtureas sensed by an oxygen sensor (not shown). The ECU 200 may, for example,control the amount of fuel injected into the engine 300 and/or theposition of a throttle valve of the engine 300. The ECU 200 may alsomonitor engine conditions such as the oil pressure and the coolanttemperature as detected by sensors (not shown). An automatic zeroemission mode is provided by the ECU 200 when the switch 20 is in theENGINE RUN position when the SOC of the battery array 30 is sufficientor when the sensors of the vehicle 10 sense areas and routes where thezero emission mode is required. The ECU 200 will turn the engine 300off, even though the switch 20 is in the ENGINE RUN position, when itdetermines that the zero emission mode is required. As discussed above,the zero emissions mode may be initiated when the SOC of the batteryarray 30 is sufficient or when designated areas or routes are entered.For example, the vehicle 10 may be equipped with sensors (not shown)responsive to signals from the global positioning system (GPS) or othersignal emitting devices that indicate that the vehicle has entered anarea or route where the zero emission mode is required.

[0065] This embodiment also includes a control panel that controls thedriving mode of the vehicle. Referring to FIG. 7, a control panel 25positioned, for example, in the operator area of the vehicle 10,includes a plurality of switches 26-29. After starting the vehicle 10 bymoving the master switch 20 to the engine run position, one of theswitches 26-29 is selected to establish a driving mode of the vehicle10. A first driving mode F1 is established by selecting switch 26. Inthis embodiment, the first driving mode F1 is established for drivingthe vehicle at lower speeds and under conditions in which the vehicle 10will start and stop frequently. A second driving mode F2 is establishedby selecting switch 27. The second driving mode F2 is established fordriving the vehicle at higher speeds and under conditions in which thevehicle is started and stopped less frequently. The ECU 200 controls theelectric motors 50 and 60 depending on which driving mode isestablished. The maximum power output and rpm of the electric motors 50and 60 in the second driving mode F2 are higher than the maximum poweroutput and rpm of the motors 50 and 60 in the first driving mode F1.

[0066] While two driving modes are shown in FIG. 7 and discussed above,any number of modes can be provided. These modes can be directed todifferent driving conditions, road conditions, weather conditions, andthe like. For example, the vehicle 10 can also be driven in a highefficiency mode that conserves energy, a high vehicle performance andpower mode for rapid acceleration, quick response, and a higher maximumvehicle speed or in a limiting mode in which the available speed,torque, or power produced is limited. The ECU 200 also stores aplurality of settings and limits for systems and devices according tovarious vehicle driving modes. For example, the ECU 200 stores aplurality of preset state of charge upper control limits UCL and stateof charge lower control limits LCL for the battery array 30 based on thecurrent vehicle driving mode.

[0067] The control panel 25 also includes a switch 28 to establish aneutral mode N. In the neutral mode N, the electric motors 50 and 60 aredisengaged by the ECU 200 and the vehicle 10 is not propelled by theelectric motors 50 and 60, even if an accelerator pedal (discussedbelow) is pressed by the operator.

[0068] A reverse mode R is established by selecting a switch 29. In thereverse mode R, the electric motors 50 and 60 are controlled to rotatein the opposite direction of the first and second driving modes F1 andF2 to propel the vehicle 10 in a reverse direction.

[0069] This embodiment may also include a second control panel forcontrolling the regenerative braking of the vehicle 10. Referring toFIG. 8, a second control panel 75 positioned, for example, in theoperator area of the vehicle 10, includes a plurality of switches 76-78.After starting the vehicle 10 by moving the master switch 20 to theengine run position, one of the switches 76-78 is selected to establisha regenerative braking mode of the vehicle 10. A first regenerativebraking mode R1 is established by selecting switch 76. In the firstregenerative braking mode R1, the regenerative braking function isturned off. The first regenerative braking mode R1 may be selectedduring icy road conditions or other hazardous weather conditions.

[0070] A second regenerative braking mode R2 may be selected by switch77. The second braking mode R2 is selected when the regenerative brakingeffort should be minimal, such as wet road conditions or when the stateof charge SOC of the battery array approaches an upper control limitUCL.

[0071] A third regenerative braking mode R3 may be selected by switch78. The third braking mode R3 is selected when the regenerative brakingefforts should be at a maximum, such as during dry road conditions orwhen the state of charge SOC of the battery array 30 approaches a lowercontrol limit LCL.

[0072] Although the regenerative braking mode has been shown as selectedby the operator, it should be appreciated that the ECU 200 may changethe regenerative braking mode when certain conditions, such as slippingof any of the wheels 11-14, are detected. Moreover, while three modesare illustrated in this embodiment, any number of modes could beemployed as desired, directed to any types of environmental conditionsand/or operating parameters.

[0073] Referring to FIG. 9, the position of an accelerator pedal 40 isdetected by a sensor 45. The sensor 45 sends a demand signal DEMindicative of the accelerator pedal 40 position, i.e., the user demand,to the MCP 220. The demand signal DEM has a value of zero when theaccelerator pedal 40 is not depressed and a maximum value when theaccelerator pedal 40 is fully depressed.

[0074] The ECU 200 sends a drive demand signal DRVDEM to the motorcontrollers 51 and 61. The drive demand signal DRVDEM follows and isproportional to the demand signal DEM of the sensor 45. However, due toa lag in the processing by the ECU 200, the instantaneous value of thedemand signal DEM from the sensor 45 may be greater than or less thanthe drive demand signal DRVDEM produced by the ECU 200 and sent to themotor controllers 51 and 61. Accordingly, there is a difference in thesignals equal to the difference between the instantaneous value of thedemand signal DEM and the value of the drive demand signal DRVDEM. Themotor controllers 51 and 61 send a drive command signal DRVCMD to themotors 50 and 60 to create torque and speed. The drive command signalDRVCMD follows and is proportional to the drive demand signal DRVDEM.The relationship between the value of the drive command signal DRVCMDand the instantaneous value of the drive demand signal DRVDEM is similarto the relationship between the drive demand signal DRVDEM and theinstantaneous value of the demand signal DEM.

[0075] The ECU 200 uses a proportional-integral-derivative (PID) controlmode to adaptively control the propulsion of the vehicle 10. The controlmode may be stored as a program in a memory of the ECU 200 and executedby the PLC 210. The proportional mode produces an output proportional tothe difference between the instantaneous value of the demand signal DEMand the drive demand signal DRVDEM. The integral mode produces an outputproportional to the amount of the difference and the length of time thedifference is present. The derivative mode produces an outputproportional to the rate of change of the difference. The PID controlmode may be applied to other systems of the vehicle 10 in addition tothe control of the motors 50 and 60 for controlling the propulsion ofthe vehicle 10 and may be applied to systems that have transientdifferences and to systems that have steady-state differences. All threecomponents, proportional, integral, and derivative, of the PID controlmode are summed and can be adjusted in real time to create a controlledoutput, thus changing the system responsiveness.

[0076] The PID control mode is provided with parameters within which thesignals necessary to control the electric motors 50 and 60, includingthe drive command signal DRVCMD, are adaptively adjusted and controlled.For example, the drive demand signal DRVDEM generated by the ECU 200 isproportional to the demand signal DEM sent by the accelerator pedalposition sensor 45. Generally, the value of the drive demand signalDRVDEM is equal to 100% of the value of the demand signal DEM. However,within the PID control mode, the value of the drive demand signal DRVDEMmay be set equal to 110% of the value of the demand signal DEM in orderto increase the responsiveness of the vehicle 10. Conversely, the valueof the drive demand signal DRVDEM may be set equal to 90% of the valueof the demand signal DEM in order to decrease the responsiveness of thevehicle 10, for example when the state of charge SOC of the batteryarray 30 is insufficient to meet a sudden increase in user demand.

[0077] Additionally, a drive command upper control limit DRVCMDUCL and adrive command lower control limit DRVCMDLCL of the drive command signalDRVCMD are adaptively adjusted by the PID control mode in response tovehicle conditions, such as the driving mode and/or an emission mode ofthe vehicle 10. The drive command upper control limit DRVCMDUCL anddrive command lower control limit DRVCMDLCL may be empiricallydetermined and dependent on service conditions, such as terrain andweather conditions, that the vehicle 10 will likely be operated under.It should also be appreciated that the PID parameters are alsoempirically determined and may be any value. For example, the PIDparameters may be determined so that the value of the drive demandsignal DRVDEM may be as low as 80% of the value of the demand signal DEMand as high as 120% of the value of the signal DEM.

[0078] An exemplary embodiment of a method for adaptively controllingthe propulsion of the series hybrid electric vehicle will be explainedwith reference to FIGS. 10-15. The control subroutines illustrated inFIGS. 10-15 are executed concurrently at predetermined time intervalsduring operation of the vehicle.

[0079] Referring to FIG. 10, a throttle control subroutine begins instep S100 and proceeds to step S110 where it is determined if the demandsignal DEM is smaller than the drive demand signal DRVDEM. If the demandsignal DEM is not smaller than the drive demand signal DRVDEM (S110:NO), the control proceeds to step S120 where the drive command signalDRVCMD to the motors 50 and 60 is increased within the PID parameters.The control then returns to the beginning in step S140. If the demandsignal DEM is smaller than the drive demand signal DRVDEM (S110: Yes),the control proceeds to step S130 where the drive command signal DRVCMDto the motors 50 and 60 is decreased within the PID parameters. Thecontrol then returns to the beginning in step S140.

[0080] Referring to FIG. 11, a battery array state of charge subroutinebegins in step S200 and proceeds to step S210 where it is determined ifthe battery array state of charge SOC is sufficient to sustain a stateof charge upper control limit UCL. If the state of charge SOC is notsufficient (S210: No), the control proceeds to step S220 where the drivecommand upper control limit DRVCMDUCL parameters are lowered. Thecontrol then returns to the beginning in step S280. If the state ofcharge SOC is sufficient to sustain the state of charge upper controllimit UCL (S210: Yes), the control proceeds to step S230 where it isdetermined if the battery array temperature is sufficient to sustain thestate of charge upper control limit UCL.

[0081] If the battery array temperature is not sufficient to sustain thestate of charge upper control limit UCL (S230: No), the control proceedsto step S220 where the drive command upper control limit DRVCMDUCLparameters are lowered. The control then returns to the beginning instep S280. If the battery array temperature is sufficient to sustain thestate of charge upper control limit UCL (S230: Yes), the controlproceeds to step S240 where it is determined if the vehicle 10 is in thefirst driving mode F1. If it is determined that the vehicle 10 is not inthe first driving mode F1 (S240: No), the control proceeds to step S250where it is determined if the drive command upper control limitDRVCMDUCL is less than a drive command upper control limit DRVCMDUCL2associated with the second driving mode F2.

[0082] If it is determined that the drive command upper control limitDRVCMDUCL is not less than the drive command upper control limitDRVCMDUCL2 associated with the second driving mode F2 (S250: No), thecontrol proceeds to step S220 where the drive command upper controllimit DRVCMDUCL parameters are lowered. The control then returns to thebeginning in step S280. If it is determined that the drive command uppercontrol value DRVCMDUCL is less than the drive command upper controllimit DRVCMDUCL2 associated with the second driving mode F2 (S250: Yes),the control proceeds to step S270 where the drive command upper controllimit DRVCMDUCL parameters are raised. The control then returns to thebeginning in step S280.

[0083] If it is determined that the vehicle 10 is in the first drivingmode F1 (S240: Yes), the control proceeds to step S260 where it isdetermined whether the drive command upper control limit DRVCMDUCL isless than a drive command upper control limit DRVCMDUCL1 associated withthe first driving mode F1. If the drive command upper control limitDRVCMDUCL is not less than the drive command upper control limitDRVCMDUCL1 associated with the first driving mode F1 (S260: No), thecontrol proceeds to step S220 where the drive command upper controllimit DRVCMDUCL parameters are lowered. The control then returns to thebeginning in step S280.

[0084] If the drive command upper control limit DRVCMDUCL is less thanthe drive command upper control limit DRVCMDUCL1 associated with thefirst driving mode F1 (S260: Yes), the control proceeds to step S270where the drive command upper control limit DRVCMDUCL parameters areraised. The control then returns to the beginning in step S280.

[0085] Referring to FIG. 12, an emission mode subroutine begins in stepS300 and proceeds to step S310 where it is determined if the vehicle 10is in a first emission mode. The first emission mode is a mode in whichthe engine 300 is at full output or where full output is allowed. If itis determined that the vehicle 10 is in the first emission mode (S310:Yes), the control proceeds to step S320 where the drive command uppercontrol limit DRVCMDUCL and the drive command lower control limitDRVCMDLCL are raised. The control then returns to the beginning in stepS370.

[0086] If it determined that the vehicle 10 is not in the first emissionmode (S310: No), the control proceeds to step S330 where it isdetermined if the vehicle 10 is in a second emission mode. The secondemission mode is a mode in which the engine 300 is at a minimum output.If it is determined that the vehicle 10 is in the second emission mode(S330: Yes), the control proceeds to step S340 where the drive commandupper control limit DRVCMDUCL and the drive command lower control limitDRVCMDLCL are modified. If the vehicle 10 was previously in the firstemission mode, the drive command upper control limit DRVCMDUCL and thedrive command lower control limit DRVCMDLCL are lowered. If the vehicle10 was previously in a third emission mode, the drive command uppercontrol limit DRVCMDUCL and the drive command lower control limitDRVCMDLCL are raised. The control then returns to the beginning in stepS370.

[0087] If it is determined that the vehicle 10 is not in the secondemission mode (S330: No), the control proceeds to step S350 where it isdetermined if the vehicle 10 is in the third emission mode. The thirdemission mode is a mode in which the engine 300 is turned off. In otherwords, the third emission mode is a zero emission mode.

[0088] If it is determined that the vehicle 10 is in the third emissionmode (S350: Yes), the control proceeds to step S360 where the drivecommand upper control limit DRVCMDUCL and the drive command lowercontrol limit DRVCMDLCL are lowered. The control then returns to thebeginning in step S370. If it is determined that the vehicle 10 is notin the third emission mode (S350: No), the control returns to thebeginning in step S370.

[0089] Referring to FIG. 13, a regenerative braking mode subroutinebegins in step S400 and proceeds to step S410 where it is determined ifthe vehicle is in the first regenerative braking mode R1. If it isdetermined that the vehicle 10 is in the first regenerative braking modeR1 (S410: Yes), the control proceeds to step S420 where feedforwardregeneration mode settings associated with the first regeneration modeR1 are lowered. The feedforward regeneration mode settings are used toraise the PID parameters to quicken the response of the system. Thecontrol then returns to the beginning in step S 470.

[0090] If it is determined that the vehicle 10 is not in the firstregenerative braking mode R1 (S410: No), the control proceeds to stepS430 where it is determined if the vehicle is in the second regenerativebraking mode R2. If the vehicle is in the second regenerative brakingmode R2 (S430: Yes), the control proceeds to step S440 where thefeedforward regeneration mode settings associated with the secondregenerative braking mode R2 are modified. If the state of charge SOC isapproaching the upper control limit UCL, the feedforward regenerationmode settings associated with the second regenerative braking mode R2are lowered. Conversely, if the state of charge SOC is approaching thelower control limit LCL, the feedforward regeneration mode settingsassociated with the second regenerative braking mode R2 are raised. Thecontrol then returns to the beginning in step S 470.

[0091] If is determined that the vehicle 10 is not in the secondregenerative braking mode R2 (S430: No), the control proceeds to stepS450 where it is determined if the vehicle 10 is in the thirdregenerative braking mode R3. If the vehicle 10 is in the thirdregenerative braking mode R3 (S450: Yes), the control proceeds to stepS460 where the feedforward regeneration mode settings associated withthe third regenerative braking mode R3 are raised. The control thenreturns to the beginning in step S470. If it is determined that thevehicle 10 is not in the third regenerative braking mode R3 (S450: No),the control returns to the beginning in step S470.

[0092] Referring to FIG. 14, a left traction control subroutine for theelectric motor 50 (left drive), in an exemplary embodiment in which thevehicle 10 is rear wheel drive, begins in step S500 and proceeds to stepS510 where it is determined if the electric motor 50 is operatingnominally. According to an exemplary embodiment of the invention, theelectric motor 50 is determined to be operating nominally if the voltageand temperature of the electric motor 50 are within predeterminedparameters. If the electric motor 50 is not operating nominally (S510:No), the control proceeds to step S520 where a drive warning and/orfaults are reset. The faults are error codes generated by the ECU 200upon detection of abnormalities, such as a short circuit in an IGBT 330or failure of an encoder 56 or 66. The control then proceeds to stepS530 where it is determined if the electric motor 50 is operatingnominally. If the electric motor is still not operating nominally (S530:No), the control proceeds to step S540 where the electric motor 50 isshut down if required and torque is shifted to the right side byincreasing the torque drive command to the electric motor 60. Thecontrol then returns to the beginning in step S595.

[0093] If after resetting the drive warning and/or faults, it isdetermined that the electric motor 50 is operating nominally (S530:Yes), the control proceeds to step S 550 where it is determined if theelectric motor 60 (right drive in the exemplary rear wheel drive vehicle10) is operating nominally. The electric motor 60 is determined to beoperating nominally if the voltage and temperature of the electric motor60 are within predetermined parameters. If the electric motor 60 is notoperating nominally (S550: No), the control proceeds to step S560 wheretorque is shifted to the left drive by increasing the drive to theelectric motor 50 and increasing upper control limits of the torque andvelocity of the electric motor 50. The control then proceeds to stepS570. If it is determined that the electric motor 60 is operatingnominally (S550: Yes), the control proceeds directly to step S570.

[0094] In step S570, it is determined if adequate traction ismaintained. Adequate traction is not maintained if excessive slippage isdetected between a rear wheel 13 or 14 and a speed reference which is avalue slightly higher than the speed of the front wheels 11 and 12. Ifadequate traction is not maintained (S570: No), the control proceeds tostep S580 where the drive to motors 50 and 60 is decreased until thespeed of the wheels 13 and 14 matches the speed reference. The controlthen returns to the beginning in step S595. If adequate traction ismaintained (S570: Yes), the drives to the motors 50 and 60 aremaintained in step S590. The control then returns to the beginning instep S595.

[0095] Referring to FIG. 15, a right traction control subroutineincluding steps S600-S695 for the electric motor 60 (right drive)corresponds to the steps S500-S595 of the left traction controlsubroutine shown in FIG. 14. The right drive is checked in steps S610and S630 to determine if the electric motor 60 is operating nominallyand the left drive is checked in step S650 to determine if the electricmotor 50 is operating nominally.

[0096] Referring to FIG. 16, a regenerative braking control subroutineincludes steps S700-S765 for determining when to operate regenerativebraking and to what power levels. An exemplary embodiment of aregenerative braking arrangement implemented on the vehicle 10 includesbattery array 30 and battery array temperature probe 30′, drive motors50 and 60 capable of producing regenerative braking, drive motorcontrollers 51 and 61, throttle input sensor 45, wheels 13 and 14, andwheel speed sensors 13′ and 14′. It will be appreciated that otherimplementations may exist, with a multiplicity of energy storage, drivemotors and other systems alternately employed.

[0097] In the exemplary embodiment described herein, the control beginsat step S700, where it proceeds to step S705. In step S705 it isdetermined if a drive motor is rotating. In the exemplary embodiment,this is accomplished by using the wheel speed sensors 13′ and 14′ tocharacterize the rotation of the wheels 13 and 14. It will beappreciated that other methods may be employed to determine if a drivemotor is rotating. If it is determined that a drive motor is rotating(S705: Yes), the control proceeds to step S710, where it is determinedif the throttle input 45 is inactive. This is used to determine if theoperator is commanding the throttle to accelerate the vehicle.Regenerative braking should only be activated if the driver is notcommanding the throttle.

[0098] If the throttle input is inactive (S710: Yes), the controlproceeds to step S715, where it is determined if the battery array 30 isoperating nominally. In the exemplary embodiment, the battery array isoperating nominally if the battery temperature sensed at the probe 30′is within a predefined range of temperature, and the battery array stateof charge is below an upper state of charge limit. If the battery arrayis operating nominally (S715: Yes), the control proceeds to step S720,where it is determined if the braking input is active. In theembodiment, the braking input is used to determine if the operator iscommanding a braking event. If it is determined that there is a brakinginput active (S720: Yes), the control proceeds to step S725, where it isdetermined if the anti-lock braking system (ABS), traction controlsystem, or other wheel spin control device or algorithm is inactive. Inthe embodiment, this determines if there are other vehicle systems orcontrols that have the potential to interfere with the regenerativebraking. If it is determined that there is one or more wheel spincontrol devices active (S725: No) the control proceeds to step S730,where regenerative braking is disabled. The control then proceeds tostep S760, where it returns to the beginning.

[0099] If it is determined that all wheel spin control devices areinactive (S725: Yes), the control proceeds to step S735. In step S735 inthe exemplary embodiment, signals are generated to allow regenerativebraking corresponding to the levels indicated by the selected mode ofregenerative braking. The control then proceeds to step S740, where itis determined if traction is maintained. In the exemplary embodiment,this is determined by using the wheel speed sensors 13′ and 14′ tomeasure the speed of wheels 13 and 14 and make a comparison. Adifference in rotational wheel speed of more than a critical percentage,for example 5%, would indicate a slipping wheel. It will be appreciatedthat other methods of determining wheel slippage may be used, and thecontrol method herein is not limited to this embodiment.

[0100] If in step S740 it is determined that wheel traction is notmaintained (S740: No), the control proceeds to step S745, where theregenerative braking command is reduced. In the exemplary embodiment,wheel traction loss may be indicative of a regenerative braking commandthat causes the wheel to lose traction on a surface of reducedcoefficient of friction, such as ice. The control then proceeds to stepS760, where it returns to the beginning. If in step S740 it isdetermined that wheel traction is maintained (S740: Yes), the controlproceeds to step S750, where it is determined if the battery array isoperating nominally. In the exemplary embodiment, a high battery arraystate of charge indicates reduction of regenerative braking is necessaryto reduce the amount of energy being transferred from regenerativebraking into the battery array. If it is determined in step S750 thatthe battery array is not operating nominally (S750: No), the controlproceeds to step S755 where regenerative braking is reduced. The controlthen proceeds to step S760, where it returns to the beginning. If it isdetermined that the battery array is operating nominally (S750: Yes) thecontrol proceeds to step S760, where it returns to the beginning.

[0101] Referring to FIG. 17, a regenerative braking fault controlincludes steps S800-S870 for determining if vehicle components arefaulted, and controlling the regenerative braking based upon the faultstatus. An exemplary embodiment of a regenerative braking arrangementimplemented on the vehicle 10 includes battery array 30 and batteryarray temperature probe 30′, drive motors 50 and 60 capable of producingregenerative braking, drive motor controllers 51 and 61. It will beappreciated that other implementations may exist, with a multiplicity ofenergy storage, drive motors and other systems alternately employed.

[0102] In the exemplary embodiment described herein, the control beginsat step S800, where it proceeds to step S810. In step S810, it isdetermined if the battery array 30 is in a warning state or faulted. Ifthe battery array is faulted (S810: Yes), the control proceeds to stepS820 where it is determined if the battery array is depleted. In anexemplary embodiment, the battery array may generate warnings or faultsif the state of charge of the battery array falls below a predeterminedlower state of charge limit. It will be appreciated that other systemsfor determining battery array warnings or faults may also be used, andother conditions or states may also cause battery array warnings orfaults. If the battery array is depleted (S820: Yes), the controlproceeds to step S830, where the regenerative braking command isincreased. The control then proceeds to step S870, where it returns tothe beginning. If the battery array is not depleted (S820: No), thecontrol proceeds to step S840, where the regenerative braking isdisabled. The control then proceeds to step S870, where it returns tothe beginning.

[0103] If it is determined that the battery array 30 is not in a warningor fault state (S810: No), the control proceeds to step S850 where it isdetermined if the drive motor is in a warning state or faulted. In anexemplary embodiment, the drive motor may generate warnings or faults ifthe drive motor temperature exceeds a predetermined limit. It will beappreciated that other conditions or states may also cause drive motorwarnings or faults. If the drive motor is in a warning or fault state(S850: Yes) the control proceeds to step S860 where the regenerativebraking is disabled. The control then proceeds to step S870, where itreturns to the beginning. If the drive motor is not in a warning orfault state (S850: No), the control proceeds to step S870, where itreturns to the beginning.

[0104] Referring to FIG. 18, a regenerative braking temperature controlincludes steps S900-S965 for determining the appropriate level ofregenerative braking to be provided in response to system componenttemperatures. An exemplary embodiment of a regenerative brakingarrangement implemented on the vehicle 10 includes battery array 30 andbattery array temperature probe 30′, drive motors 50 and 60 capable ofproducing regenerative braking, drive motor controllers 51 and 61,internal combustion engine 300, generator 310, and generator controller320. It will be appreciated that other implementations may exist, with amultiplicity of energy storage, drive motors and other systemsalternately employed.

[0105] In the exemplary embodiment described herein, the control beginsat step S900, where it proceeds to step S905. In step S905, it isdetermined if the battery array 30 temperature is nominal. If it is not(S905: No), the control proceeds to step S910, where it is determined ifthe battery array temperature above a predetermined limit. If it isdetermined the battery array temperature is not above a predeterminedlimit (S910: No), the control proceeds to step S915, where theregenerative braking command is increased. The control then proceeds tostep S965, where it returns to the beginning. If the battery arraytemperature is above a predetermined limit (S910: Yes), the controlproceeds to step S920, where the regenerative braking command isreduced. The control then proceeds to step S965, where it returns to thebeginning.

[0106] If in step S905 it is determined that the battery arraytemperature is nominal (S905: Yes), the control proceeds to step S925where it is determined if the cooling system temperature is nominal. Ifit is not (S925: No), the control proceeds to step S930, where it isdetermined if the cooling system temperature is above a predeterminedlimit. If it is determined the cooling system temperature is not above apredetermined limit (S930: No), the control proceeds to step S935, wherethe regenerative braking command is increased. The control then proceedsto step S965, where it returns to the beginning. If the cooling systemtemperature is above a predetermined limit (S930: Yes), the controlproceeds to step S940, where the regenerative braking command isreduced. The control then proceeds to step S965. where it returns to thebeginning.

[0107] If in step S925 it is determined that the cooling systemtemperature is nominal (S925: Yes), the control proceeds to step S945where it is determined if the drive motor temperature is nominal. If itis not (S945: No), the control proceeds to step S950, where it isdetermined if the drive motor temperature is above a predeterminedlimit. If it is determined the drive motor temperature is not above apredetermined limit (S950: No), the control proceeds to step S955, wherethe regenerative braking command is increased. The control then proceedsto step S965, where it returns to the beginning. If the drive motortemperature is above a predetermined limit (S950: Yes), the controlproceeds to step S960, where the regenerative braking command isreduced. The control then proceeds to step S965, where it returns to thebeginning.

[0108] It will be appreciated by those skilled in the art that the ECUcan be implemented using a single special purpose integrated circuit(e.g., ASIC) having a main or central processor section for overall,system-level control, and separate sections dedicated to performingvarious different specific computations, functions and other processesunder control of the PLC. The ECU also can be a plurality of separatededicated or programmable integrated or other electronic circuits ordevices (e.g., hardwired electronic or logic circuits such as discreteelement circuits, or programmable logic devices such as PLDs, PLAs,PALs, DSPs or the like). The ECU can be implemented using a suitablyprogrammed general purpose computer, e.g., a microprocessor,microcontroller or other processor device (CPU or MPU), either alone orin conjunction with one or more peripheral (e.g., integrated circuit)data and signal processing devices. In general, any device or assemblyof devices on which a finite state machine capable of implementing theflowcharts shown in FIGS. 8-12 and described herein can be used as theECU. A distributed processing architecture can be used for maximumdata/signal processing capability and speed.

[0109] While the invention has been described with reference to variousexemplary embodiments thereof, it is to be understood that the inventionis not limited to the disclosed embodiments or constructions. To thecontrary, the invention is intended to cover various modifications andequivalent arrangements. In addition, while the various elements of thedisclosed invention are shown in various combinations andconfigurations, which are exemplary, other combinations andconfigurations, including more, less or only a single element, are alsowithin the spirit and scope of the invention.

What is claimed is:
 1. A method for adaptively controlling a hybridelectric vehicle including an energy generation system, a energy storagesystem receiving electric current at least from the generation system,and at least one electric motor receiving current from the energystorage system, comprising: storing an upper energy storage limit and alower energy storage limit for the energy storage system for each of aplurality of predetermined driving modes; determining a currentlyselected driving mode from the plurality of predetermined driving modes;setting the upper energy storage limit and the lower energy storagelimit for the energy storage system based on the currently selecteddriving mode; determining parameters for operation of vehicle componentswithin the currently selected driving mode; and generating commandsignals to the vehicle components for operation within determinedparameters.
 2. The method of claim 1, wherein the selected driving modeproduces high vehicle energy efficiency.
 3. The method of claim 1,wherein the selected driving mode produces high vehicle performance andpower.
 4. The method of claim 1, wherein the selected driving modeoptimizes vehicle operation in hazardous weather conditions.
 5. Themethod of claim 1, wherein the selected driving mode is a zero-emissionmode.
 6. The method of claim 1, wherein the selected driving mode limitsthe available speed, torque, or power produced.
 7. The method of claim1, wherein the selected driving mode allows the vehicle to operate in anautomated guidance mode.
 8. The method of claim 1, wherein the selecteddriving mode allows the vehicle to be operated from a remote locationvia radio or other signaling method.
 9. The method of claim 1, furthercomprising: determining the driving mode based upon an operator inputsignal.
 10. The method of claim 1, further comprising: determining thedriving mode based upon an externally supplied signal.
 11. The method ofclaim 1, further comprising: determining the driving mode based uponvehicle system states or conditions.
 12. The method of claim 1, furthercomprising: determining the driving mode based upon vehicle sensorstates or measurements.
 13. The method of claim 1, further comprising:determining whether the currently selected driving mode will cause anunsafe vehicle condition; determining another driving mode that willeliminate the unsafe vehicle condition and; changing the current drivingmode to the another driving mode.
 14. The method of claim 1, wherein anupper torque limit, power limit, or speed limit for operation of theelectric drive motor is specified for the currently selected drivingmode.
 15. The method of claim 1, wherein an upper energy generationlimit for the energy generation device is specified for the currentlyselected driving mode.
 16. A hybrid electric vehicle, comprising: anenergy generation system; a energy storage system that receives electriccurrent at least from the generation system; at least one electric motorthat receives current from the energy storage system; and a controllerthat: stores an upper energy storage limit and a lower energy storagelimit for the energy storage system for each of a plurality ofpredetermined driving modes; determines a currently selected drivingmode from the plurality of predetermined driving modes; sets the upperenergy storage limit and the lower energy storage limit for the energystorage system based on the currently selected driving mode; determinesparameters for operation of vehicle components within the currentlyselected driving mode; and generates command signals to the vehiclecomponents for operation within determined parameters.
 17. The vehicleof claim 16, wherein the selected driving mode produces high vehicleenergy efficiency.
 18. The vehicle of claim 16, wherein the selecteddriving mode produces high vehicle performance and power.
 19. Thevehicle of claim 16, wherein the selected driving mode optimizes vehicleoperation in hazardous weather conditions.
 20. The vehicle of claim 16,wherein the selected driving mode is a zero-emission mode.
 21. Thevehicle of claim 16, wherein the selected driving mode limits theavailable speed, torque, or power produced.
 22. The vehicle of claim 16,wherein the selected driving mode allows the vehicle to operate in anautomated guidance mode.
 23. The vehicle of claim 16, wherein theselected driving mode allows the vehicle to be operated from a remotelocation via radio or other signaling method.
 24. The vehicle of claim16, wherein the controller: determines the driving mode based upon anoperator input signal.
 25. The vehicle of claim 16, wherein thecontroller: determines the driving mode based upon an externallysupplied signal.
 26. The vehicle of claim 16, wherein the controller:determines the driving mode based upon vehicle system states orconditions.
 27. The vehicle of claim 16, wherein the controller:determines the driving mode based upon vehicle sensor states ormeasurements.
 28. The vehicle of claim 16, wherein the controller:determines whether the currently selected driving mode will cause anunsafe vehicle condition; determines another driving mode that willeliminate the unsafe vehicle condition and; changes the current drivingmode to the another driving mode.
 29. The vehicle of claim 16, whereinan upper torque limit, power limit, or speed limit for operation of theelectric drive motor is specified for the currently selected drivingmode.
 30. The vehicle of claim 16, wherein an upper energy generationlimit for the energy generation device is specified for the currentlyselected driving mode.